Red Mud Slurry for Flue Gas Desulfurization and Denitrification
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current methods for desulfurization and denitrification of alumina calcination flue gas in the aluminum industry face challenges such as low efficiency, high ozone consumption, and the inability to effectively recycle red mud solid wastes, with existing technologies failing to simultaneously achieve both desulfurization and denitrification efficiently.
Innovation Solution
A system utilizing double-tower staged absorption with red mud solid wastes as absorbents, combined with ozone, where ozone is mixed with flue gas in two stages to oxidize NOx and SO2, allowing for synergistic absorption and subsequent catalytic reactions to achieve deep desulfurization and denitrification without additional additives.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If wet and semi-dry desulfurization technologies using calcium-based desulfurizer are applied, then desulfurization can be achieved, but construction and operation costs are high
Solution Approach 1:
The invention converts harmful red mud waste (with high pH and alkalinity) into a beneficial desulfurization absorbent. The red mud, which would normally be disposed of as solid waste, is now used to absorb SO2 from flue gas, transforming an environmental liability into a resource that reduces both waste disposal costs and desulfurization costs.
Solution Approach 2:
The red mud absorbent utilizes its own inherent chemical properties (high pH and alkalinity) to perform desulfurization without requiring additional chemical additives or complex preparation processes. The absorbent serves itself by using its natural composition to neutralize and remove SO2 from the flue gas.
2Device complexity
If SNCR technology is applied for denitrification, then the process is simple, but denitrification efficiency is low and ammonia escape occurs
Solution Approach 1:
The invention changes the chemical parameters of the denitrification process by using alternative reductants (urea or formate) instead of traditional ammonia, and by conducting the reaction in a liquid-phase slurry system rather than gas-phase injection. These parameter changes improve denitrification efficiency while maintaining process simplicity and reducing ammonia escape issues.
3Productivity
If SCR denitrification technology is applied, then denitrification efficiency can reach more than 70%, but an SCR reactor needs to be added which will have a potential impact on production processes
Solution Approach 1:
The invention merges the desulfurization and denitrification processes into a single integrated system using the same red mud slurry absorbent for both functions. This combination eliminates the need for separate SCR reactors and multiple treatment systems, achieving high efficiency for both SO2 and NOx removal while simplifying the overall production process.
4Object-affected harmful factors
If oxidative denitrification technology is applied, then simultaneous desulfurization and denitrification can be achieved, but ozone consumption is high
Solution Approach 1:
The red mud slurry acts as an intermediary medium that facilitates both desulfurization and denitrification simultaneously. The slurry provides a liquid-phase environment where oxidants can efficiently react with both SO2 and NOx, improving the utilization efficiency of ozone and reducing overall consumption compared to gas-phase oxidation methods.
5Quantity of substance
If red mud is used as absorbent for desulfurization, then construction and operation costs are reduced, but the ability to simultaneously achieve denitrification is insufficient
Solution Approach 1:
The red mud slurry absorbent is designed to perform multiple functions simultaneously: it serves as both a desulfurization agent and a denitrification medium. The same absorbent material removes both SO2 and NOx from the flue gas, making the system universally effective against multiple pollutants without requiring separate treatment systems.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach achieves high purification efficiency, reduces ozone consumption, and enables the recycling of red mud, resulting in a flue gas with SO2 concentrations below 8 mg/m3 and NOx concentrations below 90 mg/m3, with desulfurization efficiency over 96.8% and oxynitride removal efficiency above 82%, while minimizing operational costs.
Implementation Method 1
ozone is mixed with flue gas in two stages to oxidize NOx and SO2
Implementation Method 2
double-tower staged absorption with red mud solid wastes as absorbents
Implementation Method 3
allowing for synergistic absorption and subsequent catalytic reactions
Implementation Method 4
subsequent catalytic reactions to achieve deep desulfurization and denitrification
Data Source
AI summary
Disclosed are a system and a method for desulfurization and denitrification of an alumina calcination flue gas, and a use. The system comprises an ozone generator, a red mud pre-impregnation slurry scrubbing tower, and a red mud pre-impregnation tank and a red mud pre-impregnation clear liquid scrubbing tower. NOx in a flue gas is oxidized into a high valence oxynitride by ozone, and with the red mud as an absorbent, the synergistic absorption of SO2 and NOx in the flue gas is achieved, while the dealkalization of the red mud is achieved. By means of the synergistic catalytic oxidation of metal ions such as Fe3+ in a red mud slurry and ozone, the synergistic absorption of sulfur and oxynitride is prompted; and the use of a structure of staged absorption in two towers overcomes the problem of the difficulty in absorbing NO2 with a low O3/NOx molar ratio.